Offset of 3/8" hold down screw from optical axis, for Arri cameras and other cameras.

[Gregg MacPherson]

The 3/8" screw thread in the camera base for fixing to release plate etc. Does anyone know the  precise horizontal offset between that (centre) and the optical centre?  If you have a dimension, is it  from common knowledge, or a factory spec, or was it measured. If measured, what sort of accuracy?

Are all the Arri cameras the same offset? Have other manufacturers copied that for their designs? If they are not all the same, I'm wondering what the offsets are for Movicam, Aaton and Eclair (NPR/ACL). Another way to approach the question is to ask whether bridge plates made for Arri cameras will have the matte box aligned with the optical axis when fitted to other cameras.

Was the offset idea carried over to some digital cameras or all?

Thanks for any thoughts,

Gregg